1 Principles of on-site cold regeneration technology at the grassroots level
Road cold recycler technology uses a one-time crushing method to mill, dig, and crush the pavement mixture on the original pavement in situ, and then mix it with a certain amount of regenerant, cement, water (or adding emulsified asphalt) and bone. The material is processed by a Road cold recycler machine according to the set thickness, and then it is shaped, rolled, and cured at a later stage, so that it can meet the technical requirements of the design roadbed structure layer. Application abroad has proved that grass-roots regeneration technology is an important part of sustainable development of highway construction and maintenance. It also has important practical significance in China:
1) Save resources. Base Road cold recycler technology can maximize the use of waste asphalt mixture, save a large amount of sand and gravel, reduce a large amount of energy consumption, and each asphalt concrete pavement that is put into operation and enters into maintenance and repair period is a potential renewable energy base.
2) Protect the environment. The old asphalt pavement cold-recycling base course technology reuses the old asphalt mixture to prevent the pavement waste from polluting the waste sites and the surrounding environment, effectively protecting woodland and cultivated land, and maintaining natural landscape and ecological environment is of great significance. The ecological environment damage caused by the development of transportation and economic development has aroused great attention from all walks of life, and it is urgent to resolve the contradiction between highway construction and environmental protection.
2Construction technology for Road cold recycler of grassroots
The site Road cold recycler construction process has a lot to do with the Road cold recycler machine selected. In this project, the German Wittgen company's WR2500 Road cold recycler machine is used.
1) On-site cold-recycling grassroots construction supporting machinery: one Wirtgen WR2500 type regeneration machine. Four watermills, one PY180 grader, one 20t tire roller, one YZ14 vibration roller, one YZ18 vibration roller, 30 loads One machine. In this overhaul project, pre-paved cement is used for Road cold recycler; the recycling machine completes milling, crushing and mixing of old and new materials: the rollers complete the final compaction of the recycled layer.
2) Construction process of Road cold recycler: crushing old pavement-YZ14 roller compactor-leveler leveling-YZ18 roller compactor-paving cement-Road cold recycler machine with water mixing-YZ14 roller compactor-leveler leveling-YZ18 roller compactor- 20t tyre roller compacts one or three round rollers compacts one health. The paving cement adopts the grid method, and the cement dosage is controlled by 4%, which is 25t / 1000m. The specific operation method is to determine the number and spacing of the rows of cement according to the width of the cold recycled layer, draw a grid, and spread the cement evenly.
The Road cold recycler machine mixes the old road material and cement with water. The relevant test personnel should immediately test the water content on site to make the cold recycled water content 1% ~ 2% higher than the optimal water content to meet the cement hydration. The need for action, while making up for the loss of water content during rolling. The walking speed of the regenerator is controlled at 6m / min during mixing. The waterwheel is connected with a water belt in front of the cold regenerator and is synchronized to add water to the cold regenerator. The connection, removal and installation of the waterwheel and the cold recycler are selected at the beginning of each T section.
After the cold recycled mixture is evenly mixed, the pressure is exhausted once with YZ14 vibratory roller, and the speed is controlled at 3km / h. If the moisture content is found to be uneven or uneven during the depressurization process, the supplementary material should be loosened together with its lower layer mixture for 10em, scraped and then compacted. After depressurization, use a grader to level the design height to meet the requirements. design standards.
3) Rolling compaction: Rolling compaction follows the principle of light first, then heavy, slow first, and then fast. The voltage is stabilized once with YZ14 vibratory roller, four to five times with YZ18 vibratory roller, two times with static pressure by three-wheel roller, and 20t tire roller Press twice. When rolling, pay attention to the width of the wrong axis, and then roll from the side of the road to the center of the road in turn. After the final pressing, the Road cold recycler layer should be smooth and smooth, and the surface has slurry exuding. Note that the final pressing completion time cannot exceed the cement final setting time. After the compaction is completed, the sand filling method is used to determine the compaction degree to ensure that the compactness meets the design requirements.
4) Construction time control: During the construction of the test section, the average speed of the cold recycler becomes 6m / min. During the construction process, unreasonable downtime and scraping time should be minimized to ensure that the construction time of each paragraph is generally within 4.5 hours.
5) Health: After 4 hours of rolling (depending on the temperature), it can be covered with damp canvas and other suitable damp materials. The covering material should be kept moist throughout the health period. Waterwheel can also be used for direct water conservation on the cold regeneration layer. Traffic is forbidden for 7 days, health is maintained all day, and the surface is always moist
3 Benefit analysis of on-site Road cold recycler technology
During the overhaul of the Huangyezhuang to Tangyin section of the Anyang territory of the S302 Gezui line, good results were obtained due to the use of on-site cold regeneration technology:
The first is to fully utilize waste materials, effectively saving natural resources such as sand and gravel mining and a large amount of land resources occupied by waste materials:
The second is to improve the operating efficiency, shorten the construction period, and open to traffic more than 20 days ahead of schedule;
The third is to reduce the construction cost. It is estimated that the cost per square meter is reduced by 7-8 yuan, and good economic benefits have been achieved. The adoption of new road mixing cold regeneration technology has filled the gap in the history of highway construction in Anyang, explored new ways for large-scale old road renovation and accumulated new experience.